Friction gear



A. BUCHI FRICTION GEAR Dec. 4, 1951 5 SheetS -Shee't -1 Filed June 30, 1947 INVENTOR.

s EvAi A. BUCHI FRICTION GEAR Dec. 4, 1951 3 Sheeis-Sheet 2 Filed June 30, 1947 A. BUCH] FRICTION GEAR Dec. 4, 1951 3 Sheet-Sheet 5 Filed June 50, 1947 INVENTOR.

Patented Dec. 4, 1951 oer-ice;

v FRICTION GEAR Alfred Buchi winterthur, Switzerland Applicationjjune 30, 1947; Serial N0.'757,979

In Switzerland June-194s i (o1. 74-May- I 10 Claimsl. 1

Theinventioniherein described refers to trio-- tion rolle'r gears especially for machines, such'as rotary blowers, pumps, and thelike, onwhich highicircumferential velocities prevail but which have-Ito transmit relatively light circumferential forces (torque) between the-driving and driven parts. According'to-this invention the construc-v tionsis made in such a mannerthat at least the gearing stage' a with the 1 highest J speeds: is do signed as a friction roller gear; andlthe'small friction rollerr'is fastened to the-shaft of the highespeedrmachineryi Around this smalllfrictionroller, a plurality of friction rollers-or larger size' are arranged which are being pressed ra dially upon the small roller insuch' a manner that all thevforces exerted'in pressing the rollers together are counteracting each other with respect to'theaxis of the central friction roller." 'The: remaining stages of the-gear inwhicht largertorquesbut slower rotaryspeeds prevail can be. constructed in various ways,- for instance, as -farqas possible in form of friction gearing, or inform oftooth gearing, hydraulic gear, etc:

The object-of this invention can also be de-'- vised-in sucha manner that preferably directly near the highest speed transmission stage there will be at least-one additional frictionrroller gear of-theasame type for the next slower gearing;

stage. The large roller of the-lattermaybe ar-' ranged coaxially with and in the extension of are supported incommon bearings. In-this man ner'the larger friction roller gears ofthe'high est-, gear-transmission stage can be pressed together with the smaller friction rollers of the next lower transmission stage against the -two coaxially arranged central friction rollers ofthetwo stages The pressing forces of the outer- (planetary) friction-'rollerswill be made equalanddirected a so that the resulting. forces with regard to the central. friction roller-axis cancel each other out: The inner, free extension of the shaft with highest rotational speed maybe-'sup ported by bearingsdirectly within the largefriction: roller of the second highest transmission stage. The latter friction roller mayalso sur round the shaft and contain at'least-one of its bearings The outer friction rollers-of the sec-,

nd highest speed transmission stage and the friction rollers of the highest transmission stage,

w c a con e wi tea ery. b

2 pressed against the :corre'spondin'g inner: rollers by a common device. It can bearran'gedthat the smaller "friction" rollers are *pressed against their?"matchirugr rollers with. greater force; and

the larger frictionrollers are pressed against their matching; rollers with lighter "force, the

forces being so distributed that both gearstransmit approximately the "same friction moments. A resilient coupling may be incorporated in-at least one suitableplace'in the-gear transmission; so that the" torques to be transmitted through the friction "roller gears specificallylduring acceleration and/or deceleration of thedrivenmachinery can be limited to an'amount The planetary friction rollers which are pressing upon the centrally arranged rollers may" be mounted on axes parallel to the central axis'but with eccentrically supported shafts, wherebyithe necessar'y adhesion pressures are: obtained by rotation of these eccentri'cally supported shafts under the: influence of preferably adjustable springs.

The pressing force between the outer friction rollers and the central rollers can be obtained by springs or similar devices which can bear ranged to press; for instance, upon bearingparts whichare' radially guided inthe gear casing and which support the outer (planetary) friction rellerse Theouter friction rollers can also be supported in levers each of which may be supported' itself at such fulcrum point or fulcrum:

shaft that these friction rollers aredisplaceable radially with respect totheir matching rollers: This-radial; motion will also be obtained preferably through springs or the like acting upon these levers :by-way of a ball joint. By usingna ball-type 'fulcrumon these levers it can also be arranged that-all the friction rollers working-together will always have sure line contact- (perfect contact along theirentire axial length); The bearing support of the outer friction rollers in the gear casing'mayalso be arranged-in a resilient manner bythe use of springs or other elastic material-,to insure a perfect, automatically adjustable-contact of all these a friction;-

rollers..

Theouter friction rollers can also be pressed upon theinner friction rollers by way of a com- This can also beaccomplished, for instance,

by one'or, in case-of two roller gear stages; by:

two-:cantilever rings" or the like, from which rings multiple springs are arranged topress upon;

3 the bearing parts of the outer friction rollers. The outer rollers or their bearings respectively can also be pressed upon the inner friction rollers by annular springs acting radially towards the inside.

The friction roller gearing can be equipped with automatic feeding devices for the type of lubricating oil suitable for it. Any desired type of bearings (sleeve, ball, roller, etc. bearings) may be used for the various shafts of this gear.

The friction roller gear of this type is simple in manufacture since it uses only round, turned parts. It is much less noisy than comparative tooth gear transmissions. rollers and bearings will be at a minimum because the pressures exerted between rollers are counteracting and cancelling each other. A certain degree of wear of the friction rollers and bearings will be permissible because of the employment of elastic means (springs, etc.) for maintaining proper contact and pressure between the rollers.

. In --the accompanying drawings, the object of this invention is illustrated in various forms by the nine figures hereunder described; however, it is not limited to the forms shown in these figures:

Correspondin parts have been given the same number.

.Fig. 1 shows an axial section through a friction roller gear with a single friction roller stage.

Figs. 2 and 3 show a friction roller gear with two friction stages, whereby Fig. 2 shows an axial section along the line 1-1 of Fig. 3, and Fig.' 3 shows a radial section along' lines II.II of Fig.2.

2 Fig. 4" represents an axial section through a gear of different type, similar to the one shown in Figs. 2 and 3.

Fig. 5 shows a detail of a different possible type of gearing for the friction rollers.

Figs.' 6 and '7 illustrate a different embodiment of this invention, whereby Fig. 6 shows a radial section along line VIVI of Fig. '7, and Fig. '7 shows an axial section along line VIIVII of Fig. 6;"

Figs. 8 and 9 show radial sections through one of the other possible'embodiments of the invention.

" In Fig. 1; the driven shaft I of the high-speed blower wheel is supported by bearings 2 and 3. On this shaft I, a friction roller 4 is arranged which is driven by multiple outer friction roller 5. These friction rollers 5 are attached to tooth gears 6 which are part of the second highest transmission stage of the gear. The friction rollers 5 are keyed upon tooth gears 6, the latter are lined with bushings I and rotating around the shafts 8. These shafts 8 are rotatably supported on one hand at point 9 in the gearing casing ID, on the other hand in the adjusting levers II via' the pins I2. 'The middle part of shafts 8 is, as illustrated later in Fig. 3, arranged eccentrically to the pins 9 and I2. The adjusting levers I I, which are keyed upon shaft pins i2, are supported free to rotate at I3 in the gear casing cover I4. and'accordingly of shafts 8, 9 and I2 will press the friction rollers 5 towards the driven friction roller 4. Since the tooth gears 6 are rigidly connected with friction rollers 5, they will also be radially displaced by the rotation of shafts 8, 9 and I2. Consequently these tooth gears 6 will engage more or less closely with the drivingtooth-gear I5. Since, however, the radial Rotation of the adjusting levers II' Wear of the friction supported at I9 by a bearing in the gear casing cover I4 and at 20 by a bearing in the ear casing part 2|.

Figs. 2 and 3- show a friction roller gear in which the two highest speed transmission stages ahead of the driven blower wheel are friction roller gears. The driven roller 4 of the highest speed stage is fitted upon the driving shaft I of the blower wheel. Roller 4 is supported by bearings 2 .and 3. The latter bearing 3 is located within friction roller I5 of the second highest transmission stage. The driving shaft I8 of this friction roller is supported coaxially to shaft I. Around this friction roller 4 and I5 are arranged, as shown in Fig. 3, three friction rollers 5 and 6. respectively, each radially displaced from rollers 4 and I5. The friction rollers 5 and 6' are integral, or they are rigidly attached to each other, and rotatably supported on shafts 8. These shafts 8 have end pins 9 and I2. The pins 9 are supported in bushings 22, and the coaxially arranged pins I2 are supported within adjustable levers II. The latter are rotatably supported in the gear casing cover I4. The levers I I are rigidly keyed together with the pins I2. The middle part of the friction roller shafts 8 may be eccentric to their outer pins 9 and I2 in such a way that by suitable rotation of'lever II the friction rollers 5 and 6' are being pressed against the central friction rollers 4 and I5 respectively. The friction roller gear shown here is also equipped with its own lubricating oil feed. Gear pump 23 serves as a lubricating oil pump. This pump feeds lubricating oil through pipes 24 and drill holes 25 and 26 to the various bearing points. Lubrication of the friction rollersis obtained in the shown example by spray lubrication whereby nozzles 21 and 28 spray the lubr'ieating oil towards the line of contact of the fric'-' tion rollers of the two stages. In case of an em bodiment according to Figs. 2 and 3 it is assumed that the third highest transmission stage consists of a tooth gear transmission. Thereby I6 is the driving tooth gear, I1 the driven gear. Tooth gear I7 is now bein driven on shaft I8 provided with a slip coupling 29. One half 39' of the coupling sits on shaft 3| of tooth gear I1, and the second half 32 of this coupling is keyed upon shaft I8 of the second highest speed transmission stage I5, 6'. The two coupling halves 30 and 32 are pressed upon each other by spring 33. The tension of spring 33 can be adjusted with the help of nut 34. The tension of spring 33 will be so adjusted that the proper functioning of all the friction roller gear stages is assured, i. e. in such a manner that under no" circumstances, not even in case of acceleration or deceleration of the speed of the engaged machines, can there be any slipping of the friction As is illustrated in Fig. 2, the shown gear is suitable'for' driving a blower impeller -35,-and

ing ribs -36.: However, liquid cooling-could alsobe Y 'employedn 1 Fig; 3 illustrates also the de'tailed design of adjusting-"levers, ll which are rotatably: supported:along cylindrical surfaces 31 concentri- "cally with shaft pins 9-and I2. The shaftparts 8, which: are eccentrically arranged (to pins "*9 and l2),are shownin-dash and-dottedlines. The springs BB act' upon levers I I. Thesprings can; be adjusted fromthe outside by was" of screws 395m such a manner-as to create sufficiently-high pressures between the -frlction rollers-to perm-it transmission ofthe driving torques; These pressures are adjusted as equally as possible. The second highest transmission gear stage "(friction rollers l, 6") requires higherroller-pressures than the highest-transmission stage because theiriction rollers 5 and 4-of theda-tter have higher circumferential velocities; and the driving friction rollers 5'fhave larger-diameterthan 6". Consequently, the latter-rollers-(Ei) transmit smaller circumferential and"friction--forces.- Now, i n orderto exert on the friction rollers "the properpressures, i. e. dlfierent pressure for the two transmission stages, the position of the springs 38. which produce these pressures is displaced axially towards the second highestytransmission stage in such a; v,,w ay,that the proper pressures are obtained on bothfriction roller gears.

Fig. i shows an embodiment. similar to the one given in Figs.,2"andj3. In this example the gear casing I9 and its cover H! are divided inthe middlgat 4U. This division is made to act also as centering device for vthe two parts Ill and. l4. Furthermore, this figure illustrates the manner which bearing bushings AZifor thepins '9, and 41' forjthe adjusting. levers H; ar fit di Qe1asticJ0r re ili n pieces 44' and 43." Now as the springs 38 exert pressure upon the,. adjusting, levers H, they try to turn shaft 8, 9,12. Since the shaft section 8 is eccentrically arranged to shaft pins 9 and I2, the two rollers 5 and 6 are thus moved more closely tQWardsthe rollers 4 and If the. rollers: 5 and 6 are elastically supported, and 'if they are pressedupon rollers 4 and I5, there is present a certain amount of adjusting margin for equalization of inaccuracies.-- In this manner a perfect contact-ofallfriction I rollers working together upontheir whole width is permanently assured-.-

-In 5 another-embodiment-of the, resilient support of bushing-42- which surrounds pin 5 is fillustratedw In this casea spirallywound sp1iing 4 4'=isplaced around the bearing; bushing 425. This spring is held from the outside through holes in; the gear casing-10$ The resiliency of the; elasticparts d3; 4-4-,-and 4 respectively need. only be very small *if'themachining of the gear has been doneaccurately Inli'igs. 6 and '7 another embodiment of this inyentionis illustrated whereby, the shaft ends 9 andlz are held in radially displaceable guide bushings 4| and 42. These bushings 4| and 42 are free to move in radial slots 45 machined into the gear casing H! or into the gear casing cover !4 respectively. Upon these guide bushings 4! act, from the outside, springs 38 and 38" respectively. By these spring forces the roller pairs 5 and 6' are being pressed towards the centrally: supported friction" rollers 4' and I5 in such a manner that proper-'- friction forces are-2. created at the two transmissionstages. Springs=38i must. press: harder. thanrsprings 38" ImFi-g; 7 :it: will alsoxbe shown loy '5 thatdh rect...lines-;can also befitted ito thefrictionirollers:

IrrFigzBLanother way of the pressing the outer frictionarollerssupon"the inner ones is illustrated merelyin a-radial section; In this case the friction rollers and .5 'f are rotatably supported "in levers. H: which move around fulcrum points 46. Springs 38" actupon the outer ends .41 (of thlesexl'evers Il The fulcrum-points of levers-1 I. may be made -in' formof cylindrical pins or :of ball joints." In case of the latter design, friction-:rollers 5 and 6" can'adjust' them selvesv accurately to the friction rollers 4 "and l5' under the effect of "springs '38"? In=Fig; 9 another form of the invention which is -.pri r1cipally' similar to'th'e one illustrated -in Fig; '7 is-shown; Springs 38 and the springs 38 (not-shown) are not resting outside upon thecyl-ihdrical-wall of the gear casing lilproper but instead on two rings 48 which are freely supported by -three springs 38" and 38 each.

' Alternatively. a single such ring could be ar ranged.- By this construction I can'assure that friction rollers 5 and '4; and 6' and'l5'; can-be pressed' upon'each' other with exactly the same fo'rcesi e." that the springs 38 and 38-" respeetively can-be tensed equally; To prevent ringid-from rotating, slots 49 are machined into it, into which engage key-type protrusions 59 fromthe-blower casing ll].

The friction-rollers may have metallic sur faces-er they may be fitted with friction lin ingss -They-ma-y be-madein full or inpart out of any elastic material, or they mayhave some resiliency in their adjustment with respect to their counter rollers-on 'accountoftheir construction;

i The object "ofthis invention may preferably alsobe-usedin the high-speed stages of "gears used for-speed reduction.

larger frictional roller gears about said small roller gear and in frictional contact therewith, a gear. .co,mparatively smaller. than and in axial alignment and fixedly engaged with each of said larger. roller gears to. constitute a rotatable idle wheel. unit, an axle. for. and upon which each said unit. isadaptedto rotate. a casing about.

all-said-..gears, said casing having means for suppOrting -eachrot saidaxles; said means be ing. 'displaceable at least partially radially of. the: axis:.of:the highest'speed: and driving. shafts,

spring:meansconstantly urging said axle sup' porting means, and-consequently said axles and said unitsrotatably mounted thereon, radially inwardlytoward-saidhighest speed and driv- ,7 means for both the driving shaft and the highest speed shaft.

2. Multiple stage speed transmission gear as defined in claim 1 wherein the gearing of the second'highest speed transmission stage is also of the friction roller type, and the outer rolls of the last said gearing are pressed together radially inwardly toward the axis of the highest speed and driving shafts with a higher pressure than the pressure between the rolls of the highest speed transmission stage, so that substantially equal friction moments are created between the rolls of the two stages.

3. Multiple stage speed transmission gear as defined; in claim 1 wherein the gearing of the second highest speed transmission stage is also of the'friction roller type, wherein the axles supporting the said idle wheel units do so eccentrically relative to the axis of the highest speed and driving shafts so that the pressure between the rolls constituting the two transmission stages may be adjusted by rotation of the said axles, and wherein spring means urge rotational translation of the said axles in a direction to increase the pressure between the rolls of both stages.

4. Multiple stage speed transmission gear as defined in claim 1 wherein the gearing of the second highest speed transmission stage is also of the friction roller-type, wherein the axles supporting the said idle wheel units do so eccentri- Cally relative to the axis of the highest speed and driving shafts so that the pressure between the rolls constituting the two transmission stages may be adjusted by rotational translation of the said axles, and wherein the said axles are mounted with at least one end in a lever device, spring urged to displace the shaft in a direction to increase the pressure between the rolls of both stages.

5. Multiple stage speed transmission gear as defined in claim 1 wherein the gearing of the second highest speed transmission stage is also of the friction roller type, wherein the axles supporting the said idle wheel units do so eccentrically relative to the axis of the highest speed and driving shafts so that the pressure between the rolls constituting the two transmission stage may be adjusted by rotational translation of the said axles, and wherein the said axles are mounted with at least one end in a lever device, and the said device is supported by a ball joint and is spring urged so that the rolls may move radially as Well as axially against their counter rolls.

6. The transmission gear described in claim 1 wherein the spring means are individually adjustable.

7. Multiple stage speed transmission gear for obtaining, from a driving engine, higher speeds and a relatively large driving roll on said second shaft in engagement with each other constitut ing the highest speed transmission stage and a relatively small driven roll on the first shaft and a relatively large driving roll in engagement therewith constituting the second highest speed transmission stage, the second shaft being pressed toward the first shaft to create driving friction between the rolls in both transmission stages, said second shaft being further supported eccentrically relative to the first shaft so -that the pressure between the rolls constituting the two transmission stages may be adjusted by rotation of the second shaft, and spring means, said spring means being adapted to urge rotation of the second shaft in a direction to increasethe pressure between the rolls of both-stages.

8. Multiple stage speed transmission gear for obtaining, from a driving engine, higher speeds than are delivered by the engine, comprising in combination a rotatable highest speed driven shaft, 9. second shaft parallel with the first, a relatively small driven roll on the first shaft and a relatively large driving roll on said second shaft in engagement with each other constituting the highest speed transmission stage and a relatively small driven roll on the second shaft and a relatively large driving roll in engagementtherewith constituting the second highest speed transmission stage, the second shaft being pressed toward the first shaft to create driving friction between the rolls in both transmission stages, said second shaft being further supported eccentrically relativeto the first shaft so that the pressure between the rolls constituting the two transmission stages may be adjusted by rotation of the second shaft, at least one portion of said second shaft being mounted in a lever-supported bearing, spring urged to rotate the shaft ina direction to increase the pressure between the rolls of both stages.

9. The multiple stage speed transmission gear as defined in claim 8 wherein the lever is supported by a ball joint, and the spring urges the rolls radially as well as axially against their respective counter-rolls.

10. The transmission gear as described in claim 1 wherein the comparatively large gear on the driving shaft has means within its central area for rotatively supporting one endof the highest speed shaft.

ALFRED BUCHI.

REFERENCES CITED The following references are of record inthe file of this patent: I

UNITED STATES PATENTS Great Britain May 22, 1888 

